At what temperature would most proteins start to denature?

• A. 15°C
• B. 37°C
• C. 60°C
• D. 100°C

Answer: (C)

Most proteins generally start to denature at temperatures around 60°C. This phenomenon occurs because the heat disrupts the hydrogen bonds, ionic bonds, and other interactions that maintain the protein's three-dimensional structure. At temperatures significantly above physiological levels, such as 60°C, the increased kinetic energy overcomes the stabilizing interactions within the protein, leading to a loss of its native conformation.

While 37°C is typical for the human body and a standard temperature for enzyme activity, it is not high enough to induce denaturation for most proteins. Temperatures around 100°C would typically be too high, often resulting in complete denaturation and precipitation of proteins. Therefore, the value of 60°C is consistent with the temperature range known for starting denaturation in many proteins, making it the correct choice in this context.